The present invention relates to a turbine rotor of a gas turbine and a cooling method of turbine blades of the turbine rotor. Particularly, the present invention relates to a turbine having a structure for recovering coolant cooled turbine blades.
A turbine rotor disclosed in WO 97/44569 (PCT/US97/04368) is formed by arranging a plurality of disc-shaped wheels, each of which has turbine blades fixed to an outer peripheral portion thereof, so as to be laminated to each other, and fastening the wheels by bolts which are passed through the wheels. In the turbine rotor, respective members are mounted on adjacent two of the wheels by fixing them with bolts, and a cavity is formed between the members, whereby a high temperature recovery coolant is not directly contacted with the wheels. The wheels become high in temperature during operation. When a temperature difference occurs between adjacent left and right wheels, a difference in thermal expansion occurs because of temperature elevation of the left and right wheels, and a difference in thermal elongation also occurs between the left and right wheels.
Further, a spacer forming a cavity is fixed to one of the wheels at one side thereof and to another wheel at the other side, so that when a difference in thermal elongation occurs between the left and right wheels, different displacements also occur in the two members forming the cavity, interlocking with the wheels fixed to the spacer. Here, when there is a large gap in a sealing portion of the cavity, it becomes difficult to seal the cavity, and there occurs a problem that recovery coolant leaks. When the recovery coolant leaks at the cavity, a quantity of coolant which can be recovered becomes short, and there occurs a problem that the cycle efficiency is lowered. Further, since two spacer plates between adjacent two wheels are in contact with both the supply coolant of low temperature and recovery coolant of high temperature, there is a subject to be solved that a large temperature distribution occurs in the spacer plates, thereby to cause large thermal stress and deformation.
Further, a turbine rotor disclosed in JP A 9-13902, U.S. Pat. No. 5,593,274 has such a structure that a supply cavity and recovery cavity for coolant cooling turbine blades are formed by a spacer and spacer plate, whereby high temperature recovery coolant is not directly contacted with the wheels. Here, the spacer plate contacts directly with the high temperature recovery coolant at its cavity side, so that the spacer plate becomes high in temperature and it is considered that the heat of the spacer plate is conducted to the wheels by heat conduction, whereby the wheel becomes high in temperature. Further, the spacer plate is fixed to the wheels by shrinkage fit. After the wheels and spacer become high in temperature during operation, upon occurrence of a temperature difference between the wheel adjacent to one side of the spacer plate and the spacer adjacent to the opposite side of the spacer plate, a difference in thermal expansion due to temperature elevation occurs between the wheel and the spacer, and a difference in thermal elongation also occurs between the wheel and the spacer. Further, when a difference in thermal expansion due to the temperature elevation occurs between the wheel and the spacer, a difference in displacement also occurs between the spacer and spacer plate forming a cavity. When there is a large gap in the sealing portion of the cavity, it is difficult to seal the cavity and there occurs a problem that recovery coolant leaks. Further, since both of low temperature supply coolant and high temperature recovery coolant are in contact with the spacer and the spacer plate, there is a problem that large thermal stress and deformation occur. Further, since the spacer plate has a coolant supply hole, coolant recovery hole and bolt hole each perforated therein, there is a problem that they become a cause of stress concentration and the strength becomes further weak. Further, in the above-mentioned prior arts, a stacking surface increases by providing a spacer plate between the wheel and the spacers compared with the condition under which there is no such a spacer plate. Therefore, left is a subject that bending primary critical speed of the rotor is lowered.
An object of the present invention is to reduce thermal stress occurring in wheels without increasing a stacking surface.
A turbine rotor according to the present invention comprises a plurality of turbine blades each having a coolant path formed inside and permitting coolant to flow therein, a plurality of wheels having the plurality of turbine blades arranged annularly in peripheral portions thereof and forming the turbine rotor, annular members each arranged between adjacent wheels of the plurality of wheels, and heat-resistant members provided on side surfaces of the wheels positioned at side surfaces of the annular members, and the turbine rotor is characterized in that the coolant heated through heat-exchange with the turbine blades and flowing down through the coolant paths faces the annular members.
Further, a cooling method according to the present invention is for turbine blades of a turbine rotor provided with a plurality of wheels having a plurality of turbine blades arranged annularly in peripheral portions thereof and forming the turbine rotor and annular members each arranged between adjacent wheels of the plurality of wheels, and characterized in that heat-resistant members are provided on side surfaces of the wheels positioned at side surfaces of the annular members, coolant is flowed in coolant paths formed inside the turbine blades, and the coolant heated through heat-exchange with the turbine blades and flowing down through the coolant paths is flowed so as to face the annular members.
Further, a gas turbine provided with a turbine rotor according to the present invention comprises a plurality of turbine blades each having a coolant path formed inside and permitting coolant to flow therein, a plurality of wheels having the plurality of turbine blades arranged annularly in peripheral portions thereof and forming the turbine rotor, annular members each arranged between adjacent wheels of the plurality of wheels, and heat-resistant members provided on side surfaces of the wheels positioned at side surfaces of the annular members, and is characterized in that the coolant heated through heat-exchange with the turbine blades and flowing down through the coolant paths faces the annular members.